[tex] \huge \boxed {\sf \: {Answer}}[/tex]
[tex]( {x}^{7} + 5x ^{4} - x + 2) - ( {5x}^{4} - {x}^{3} + 2) \\ ={x}^{7} + 5x ^{4} - x + 2 - {5x}^{4} + {x}^{3} - 2\\ = {x}^{7} + 5x ^{4} - {5x}^{4} + {x}^{3} - x + 2 - 2 \\ = {x}^{7} + {x}^{3} - x \\ = x( {x}^{6} + {x}^{2} - 1)[/tex]
Hope you could understand.
If you have any query, feel free to ask.
